1. Field of the Invention
Methods and systems consistent with the present invention relates to home network technology, and more particularly, to synchronizing a plurality of content directory service (CDS) devices in a home network environment.
2. Description of the Related Art
Generally, a home network is formed of an Internet protocol (IP)-based private network. In the home network, various devices used at home, such as all forms of personal computers (PCs), intelligent products, and wireless devices, are connected to a single network through a common virtual computing environment called ‘middleware’ and controlled accordingly. Middleware connects various digital devices in a peer-to-peer manner and thus enables them to communicate with each other. Related art middleware includes home AV interoperability (HAVI), universal plug and play (UPnP), Java intelligent network infrastructure (Jini), and home wide web (HWW).
In particular, UPnP network is home network technology which is expected to be most widely used in the near future. The UPnP network defines an UPnP device, an UPnP service, and a protocol between the UPnP device and the UPnP service. The UPnP network is composed of controlled devices (CDs) and a control point (CP). The CDs are home network devices, which are connected to an IP-based home network and controlled accordingly, and the CP is a device controlling the CDs. The CP requests an event, and receives the requested event. Each of the CDs performs a predetermined function at the request of the CP. If the state of a CD changes, the CD sends an event to the CP at the request of the CP.
An operational process between devices in the related art UPnP network includes advertisement, discovery, description, control, and eventing processes.
UPnP audio/video (AV) technology, which enables a user to enjoy multimedia content, such as AV content, based on the UPnP technology, is described in an UPnP AV specification. According to the UPnP AV specification, UPnP AV architecture includes a media server providing a multimedia file using a CDS, a media renderer rendering the multimedia file provided by the media server, and a CP controlling the media server and the media renderer to communicate with each other. The CDS is a service built in the media server. The CDS provides metadata of content, which exists inside or outside a home network or is stored in the media server, to the CP. The CP identifies the metadata from the CDS and requests the media renderer to render the metadata.
If a plurality of devices, which form the UPnP AV architecture described above, is used at home, there is a need for a plurality of media servers storing different content. Accordingly, there must be a plurality of CDS's. As such, a method of synchronizing content scattered over a plurality of different CDS's on a home network environment is needed.